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Coordinated X-ray, ultraviolet and optical observations of AM Herculis, U Geminorum, and SS CygniSimultaneous and quasi-simultaneous optical, UV and X-ray observations of the accreting degenerate dwarf stars AM Herculis, U Geminorum and SS Cygni are reported. The observations were obtained in March 1979, by instruments on board the Einstein Observatory and the IUE satellite, and optical properties were monitored on the ground. AM Her was found to be in a high state at the time of the observations, while SS Cyg and U Gem appeared to be in the optical low state. The presence of a strong UV excess is found in SS Cyg, U Gem and AM Her, which most likely originates from the boundary of the accretion disk in U Gem. The observed excess, with a blackbody component greater than 10 eV, is noted to be inconsistent with standard accretion disk and column models. It is suggested that nuclear burning at the surface of the white dwarf may be responsible for the excess UV flux in the three systems, with differences in spectral distributions resulting from different levels of magnetic field intensity and accretion rate.
Document ID
19810043442
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Fabbiano, G.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Hartmann, L.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Raymond, J.
(Harvard-Smithsonian Center for Astrophysics Cambridge, Mass., United States)
Branduardi-Raymont, G.
(London, University College, Mullard Space Science Laboratory, Dorking, Surrey, United Kingdom)
Matilsky, T.
(Rutgers University Piscataway, N.J., United States)
Steiner, J.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Date Acquired
August 11, 2013
Publication Date
February 1, 1981
Publication Information
Publication: Astrophysical Journal
Subject Category
Astrophysics
Accession Number
81A27846
Funding Number(s)
CONTRACT_GRANT: NAG5-5
CONTRACT_GRANT: NAS8-30751
CONTRACT_GRANT: NSG-5370
CONTRACT_GRANT: NAS8-30453
Distribution Limits
Public
Copyright
Other

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